Performance of finishing pigs in hoop structures or confinement during winter and summer was evaluated in Iowa. Hoops are large, tent-like shelters with cornstalks or straw for bedding. During summer and winter seasons for 3 yr (1998 to 2001), six trials were conducted using three hoop barns (designed for 150 pigs per pen, one pen per hoop) or a mechanically ventilated confinement barn with slatted floors (designed for 22 pigs per pen, six pens in the barn). A total of 3,518 pigs started the trials. Summer trials were June through October, and winter trials were December through April. Target stocking density was 1.11 m²/pig in hoops and 0.74 m²/pig in confinement. Identical corn-based diets were fed ad libitum from 16 to 118 kg for 127 d. Pigs were scanned before harvest for backfat and loin muscle area. When seasons were merged (season × housing interaction, P ≥ 0.05), hoop-fed pigs had more backfat (21.8 ± 0.3 vs 20.8 ± 0.2 mm; P < 0.001), smaller loin muscle area (41.3 ± 0.3 vs 43.0 ± 0.2 cm²; P < 0.001), less lean percentage (51.1 ± 0.2 vs 52.1 ± 0.1%;P < 0.001), and less yield (74.9 vs 75.8 ± 0.1%; P < 0.001) than confinement-fed pigs. When season × housing type interactions were observed (P < 0.004), summer hoop-fed pigs had greater ADG (834 ± 5 vs 802 ± 3 g/d; P < 0.001), required fewer days to 113 kg (174.9 ± 0.9 vs 178.5 ± 0.6 d; P < 0.01), had similar ADFI (2.40 ± 0.03 vs 2.35 ± 0.02 kg/d, as-fed basis) and gain:feed (G:F; 348 ± 4 vs 342 ± 3 g/kg) compared with confinement-fed pigs. Lean gain/day and efficiency of lean gain did not differ between housing systems. During winter, hoop-fed pigs had similar ADG (794 ± 5 vs 801 ± 3 g/d), required more days to 113 kg (176.7 ± 0.9 vs 172.9 ± 0.6 d; P < 0.01), had greater ADFI (2.54 ± 0.03 vs 2.35 ± 0.02; P < 0.001), less G:F (313 ± 4 vs 341 ± 3; P < 0.001), less lean gain/day (312 ± 2 vs 322 ± 1 g/d; P < 0.01), and less efficiency of lean gain (130 ± 2 vs 144 ± 1 g lean gain/kg feed; P < 0.01) than confinement-fed pigs. Percentage of mortalities and culls did not differ between housing systems. During summer, there was a trend for fewer light pigs at marketing (< 100 kg) from hoops (0.8 vs 1.7%; P = 0.10). During winter, there were more light pigs at marketing from hoops (3.9 vs 1.3%; P = 0.01) than from confinement. Bedding use in hoops was 92 and 122 kg/pig for summer and winter, respectively. Performance of finishing pigs in bedded hoop structures depends in part on thermal environment.